Let us now return to Earth.
Let us examine, for example, this verse in the surah Az-Zumar (39:21).
Hast thou not seen that God sent water down from the sky and led it through sources into the ground? Then He caused sown fields of different colours to grow.
Such notions seem quite natural to us today, but we should not forget that they were not prevalent long ago. It was not until the sixteenth century, with Bernard Palissy, that we gained the first coherent description of the water cycle. Prior to this, people talked about the theory whereby the water of the oceans, under the effect of winds, were thrust towards the interior of the continents. They then returned to the oceans via the great abyss, which, since Plato’s time, has been called the Tartarus. In the seventeenth century, a great thinker such as Descartes believed in it, and even in the nineteenth century there was still talk of Aristotle’s theory, according to which water was condensed in cool mountains caverns and formed underground lakes that fed springs. Today, we know that it is the infiltration of rainwater that is responsible for this. If one compares the facts of modern hydrology with the data to be found in numerous verses of the Qur’an on this subject, one cannot fail to notice the remarkable degree of agreement between the two.
In geology, a fact of recently acquired knowledge is the phenomenon of folding, which was to form the mountain ranges. The same is true of the Earth’s crust, which is like a solid shell on which we can live, while the deeper layers are hot and fluid, and thus inhospitable to any form of life. It is also known that the stability of the mountains is linked to the phenomenon of folding, for it was the folds that were to provide foundations for the reliefs that constituted the mountains.
Let us now compare modern ideas with one verse among many in the Qur’an that deals with this subject. It is taken from the surah An-Naba’ (78:6-7).
Have We not made the Earth an expanse and the mountains stakes?
The stakes (awtad), which are driven into the ground like those used to anchor a tent, are the deep foundations of geological folds.
Here, as in the case of other topics, the objective observer cannot fail to notice the absence of any contradiction with modern knowledge.
But more than anything else, I was struck, at first, by statements in the Qur’an dealing with living things, both in the animal and vegetable kingdoms, especially with regard to reproduction.
I must once again stress the fact, that it is only since modern times, that scientific progress has made the content of many such verses more comprehensible to us. There are also other verses which are more easily understandable, but which conceal a biological meaning that is highly significant. This is the case of the surah Al-Anbiya’, a part of which has already been quoted:
And We got every living thing out of the water. Will they then not believe : (21:30).
This is an affirmation of the modern idea that the origin of life is aquatic.
Progress in botany at the time of Muhammad was in no country advanced enough for it to be established as a rule that plants have both male and female parts. Nevertheless, we may read the following in the surah Taha (20:53).
(God is the One Who) sent water down from the sky and thereby We brought forth pairs of plants each separate from the other.
Today, we know that fruit comes from plants that have sexual characteristics (even when it comes from unfertilized flowers, like bananas). In the surah Ar-Ra`d (13:3) we read:
And fruit of every kind He made in pairs, two and two.
Reflections on reproduction in the animal kingdom were linked to those on human reproduction. We shall examine them presently.
In the field of physiology, there is one verse which, to me, appears extremely significant: one thousand years before the discovery of the circulation of the blood, and roughly thirteen centuries before it was known what happened in the intestine to ensure that organs were nourished by the process of digestive absorbtion, a verse in the Qur’an describes the source of the constituents of milk, in conformity with these notions.
To understand this verse, we have to know that chemical reactions occur in the intestine and that, from there substances extracted from food pass into the bloodstream via a complex system, sometimes by way of the liver, depending on their chemical nature. The blood transports them to all the organs of the body, among which are the milk-producing mammary glands.
Without entering into detail, let us just say that, basically, there is the arrival of certain substances from the contents of the intestines into the vessels of the intestinal wall itself, and the transportation of these substances by the bloodstream.
This concept must be fully appreciated, if we are to understand this verse in the surah An-Nahl (16:66).
Verily, in cattle there is a lesson for you. We give you to drink of what is inside their bodies. Coming from a conjunction between the contents of the intestines and the blood, a milk pure and pleasant for those who drink it.